Motor fan

ABSTRACT

A motor fan  1  of the present invention includes: an impeller  7   b  that forms an air flow; an electric motor  6  that rotationally drives the impeller  7   b;  a shroud  10  including a cylindrical casing  16  that covers an outer periphery of the impeller  7   b,  and through which the air flow passes, and a base  11  that projects from a periphery of the casing  16;  a control unit  40  that controls rotation of the electric motor  6  and is arranged on a discharge side of the base  11;  and a heat sink  50  that dissipates heat from heat dissipation pins  52  to suppress heat generation of the control unit  40,  wherein the heat dissipation pins  52  are exposed on a suction side in the heat sink  50.

TECHNICAL FIELD

The present invention relates to a motor fan that accompanies a heat exchanger such as a radiator and a condenser of, for example, an automobile, and more particularly, relates to a motor fan capable of efficiently cooling a controller that controls driving of an electric motor.

BACKGROUND ART

In a heat exchanger such as a radiator and a condenser of an automobile, a large amount of air is forcibly passed through a core by a motor fan. The motor fan guides an air flow toward the heat exchanger by covering a space between a periphery thereof and the heat exchanger with a shroud in order not to release air introduced by the motor fan to a lateral side.

A motor fan in which a rotational speed is variable includes a controller that controls driving of an electric motor. As the controller, for example, a PWM (pulse width modulation) unit is used. When the PWM unit controls driving of an electric motor, an incorporated power semiconductor switching device called a power device generates heat. To maintain performance of the PWM unit, it is necessary to cool the power device so as to keep a temperature of the power device at a permissible value or less. Therefore, the motor fan in which the rotational speed is variable has a configuration for cooling the controller including the power device that is a heat generating body.

For example, Patent Literature 1 proposes to install a controller inside a shroud, and to form a rib that guides air around the controller toward a motor fan side. Patent Literature 1 proposes that an excessive temperature rise of a heat generating body can be suppressed by forming the rib and thereby preventing stagnation of air around the controller.

Also, Patent Literature 2 has a premise that an air flow generated by a fan is caused to strike a PWM unit to forcibly cool the PWM unit by arranging the PWM unit facing a fan opening portion, and includes means capable of changing an area of the fan opening portion occupied by the PWM unit. In Patent Literature 2, for example, in order to prevent the PWM unit from disturbing the air flow, the occupied area is reduced when a large air flow rate is required.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent Laid-Open No. 2006-90243 -   Patent Literature 2: Japanese Patent Laid-Open No. 2010-151005

SUMMARY OF INVENTION Technical Problem

However, since the proposal in Cited Literature 1 is only at a level of preventing the stagnation of air around the controller, it is difficult to obtain a sufficient cooling effect.

In Patent Literature 2, since the PWM unit is forcibly cooled, cooling performance is high. However, even when the area of the fan opening portion occupied by the PWM unit can be changed to be small, it is undeniable that the air flow interferes with the PWM unit, and the air flow is disturbed. Therefore, in Patent Literature 2, the air flow rate is reduced, and noise is also inevitably generated.

The present invention has been accomplished in view of the technical problems as described above, and an object thereof is to provide a motor fan capable of efficiently cooling a heat generating body without disturbing an air flow.

Solution to Problem

A motor fan of the present invention that has been accomplished in view of the above object including: an impeller that forms an air flow from a suction side toward a discharge side that is a back side of the suction side; an electric motor that rotationally drives the impeller; a shroud including a cylindrical casing that covers an outer periphery of the impeller, and through which the air flow passes, and a base that projects from a periphery of the casing; and a controller that is arranged on the discharge side of the base, controls rotation of the electric motor, and includes a heat generating element, wherein a heat dissipater that is at least partially exposed on the suction side, and is thermally coupled to the heat generating element suppresses a temperature rise of the heat generating element.

In the motor fan of the present invention, since the heat dissipater is provided in the base outside the shroud through which the air flow passes, the heat dissipater does not disturb the air flow. Moreover, in the motor fan of the present invention, since the heat dissipater is exposed on the suction side where the heat dissipater can receive the air flow, it is possible to efficiently cool the heat generating element via the heat dissipater.

The present invention can employ at least first to third forms described below as a form in which the heat dissipater is exposed on the suction side. All the forms have a common effect that the heat dissipater can efficiently cool the heat generating element by the air flow formed on the suction side.

In the first form, while the heat dissipater is arranged on the discharge side of the base, the heat dissipater is exposed on the suction side via a through window that is formed in the base corresponding to the controller.

In accordance with the first form, since the heat dissipater is exposed on the suction side, it is possible to more efficiently cool the heat generating element.

In the second form, the heat dissipater is arranged only on the suction side of the base, and is thermally connected to the heat generating element of the controller via a heat transfer body that penetrates the base.

In accordance with the second form, since the base is penetrated only in a region corresponding to the heat transfer body, rigidity of the shroud can be increased.

In the third form, the heat dissipater is formed integrally with the shroud.

In accordance with the third form, since the shroud also exerts a heat dissipation action, it is possible to more efficiently cool the heat generating element.

In the present invention, the heat dissipater is preferably accommodated within a heat dissipater accommodation chamber that is provided in the base and retracted toward the discharge side. Since a projecting height of the heat dissipater can be increased, high heat dissipation efficiency can be obtained.

Advantageous Effects of Invention

In accordance with the present invention, since the heat dissipater is provided in the base outside the casing of the shroud through which the air flow passes, the heat dissipater does not disturb the air flow. Moreover, in the motor fan of the present invention, since the heat dissipater is at least partially exposed on the suction side where the heat dissipater can receive the air flow, it is possible to efficiently cool the heat generating element via the heat dissipater.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B show a motor fan in a first embodiment: FIG. 1A is a front view as viewed from a discharge side; and FIG. 1B is a front view as viewed from a suction side.

FIGS. 2A and 2B show a shroud of the motor fan in the first embodiment: FIG. 2A is a perspective view as viewed from the discharge side; and FIG. 2B is a perspective view as viewed from the suction side.

FIG. 3 is an enlarged view of a vicinity of a control unit of the motor fan in the first embodiment as viewed from the suction side.

FIG. 4 is an enlarged sectional view illustrating the vicinity of the control unit of the motor fan in the first embodiment.

FIG. 5 is a sectional view corresponding to FIG. 4 illustrating a motor fan in a second embodiment.

FIG. 6 is a sectional view corresponding to FIG. 4 illustrating a motor fan in a third embodiment.

FIG. 7 is a sectional view corresponding to FIG. 4 illustrating a modification of the present invention.

DESCRIPTION OF EMBODIMENTS

In the following, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

First Embodiment

A motor fan 1 for an automobile of a present embodiment will be described with reference to FIGS. 1A,1B to 4.

The motor fan 1 is arranged facing a rear side of a radiator that is omitted in the drawings, and when an air flow generated from a front toward a rear with the motor fan 1 rotationally driven passes through the radiator, heat exchange is performed between a medium flowing through an inner portion of the radiator and outside air as the air flow. Note that the front and the rear in the present embodiment are based on a direction in which the automobile travels forward, while, regarding the motor fan 1, a side facing the radiator is sometimes referred to as a “suction side”, and a back side thereof is sometimes referred to as a “discharge side”.

[Configuration . . . Motor Fan 1]

As shown in FIGS. 1A,1B and 2A,2B, the motor fan 1 includes a fan 5, a shroud 10 that accommodates the fan 5 and holds a control unit 40, and the control unit 40 that controls a rotating operation of the fan 5.

The motor fan 1 employs a structure in which the control unit 40 is arranged on the discharge side of the shroud 10, and heat dissipation pins 52 constituting a heat dissipater of the control unit 40 are exposed on the suction side of the shroud 10. Therefore, in the motor fan 1, a part of the air flow generated from the suction side toward the discharge side with the fan 5 rotating passes through the heat dissipation pins 52, so that the control unit 40 can be efficiently cooled. Moreover, in the motor fan 1, interference between the control unit 40 and the air flow can be avoided by arranging the control unit 40 at a corner 12 of the shroud 10. In the following, respective elements will be sequentially described.

As shown in FIG. 1B, the fan 5 includes an electric motor 6 that is fixed to and supported by the shroud 10 with a bolt, and a fan body 7 that is connected to a rotating shaft 6 a of the electric motor 6. The fan body 7 includes a bottomed cylindrical boss 7 a that is fixed to the rotating shaft 6 a, and an impeller 7 b that is composed of a plurality of blades projecting radially outward from an outer periphery of the boss 7 a.

[Configuration . . . Shroud 10]

The shroud 10 is a member that is integrally formed by injection-molding resin, and includes a base 11 having a mortar shape with a rectangular outer shape, and a casing 16 that is provided in a center portion of the base 11.

The base 11 guides the air flow on the suction side to the casing 16. The base 11 includes a fixing frame 13 that fixes the control unit 40 to one corner 12 out of four corners 12. The fixing frame 13 is provided on the discharge side of the base 11 so as to have a rectangular outer shape in plan view, and the control unit 40 is fixed to the base 11 by means such as fastening or bonding in a state in which the control unit 40 is mounted on a distal end of the fixing frame 13. Since a through window 14 that brings into communication the suction side at the distal end and the discharge side of the fixing frame 13 is formed, a pin accommodation chamber 15 penetrates from a front to a back of the base 11. Although the details are described later, the heat dissipation pins 52 of the control unit 40 held by the fixing frame 13 penetrate the through window 14 to be exposed in the pin accommodation chamber 15. An inner portion of the fixing frame 13 forms the pin accommodation chamber 15 that is retracted toward the discharge side with respect to a surface on the suction side of the base 11.

As shown in FIGS. 1A and 1B, the casing 16 includes an outer ring 17 that cylindrically projects from a surface on the discharge side of the base 11, and a discharge grill 18 that covers a distal end of the outer ring 17. The fan 5 is accommodated and held in a region surrounded by the outer ring 17 and the discharge grill 18 such that the fan body 7 is arranged toward the suction side.

The outer ring 17 is allowed to have high rigidity together with the base 11 by fixing a distal end of a rib 19 formed on the surface on the discharge side of the base 11 to an outer periphery thereof. The rib 19 extends toward the outer ring 17 from each of three corners 12 except the position where the fixing frame 13 is provided.

The discharge grill 18 includes a plurality of radial fins 18 a in order to rectify the discharged air flow. The discharge grill 18 is penetrated from a front to a back except a portion where the fins 18 a are provided, and the air flow generated by the fan 5 passes through the discharge grill 18 to flow to the discharge side. The fixing frame 13 to which the control unit 40 is fixed is located at the corner 12 outside the discharge grill 18, so that the air flow passing through the discharge grill 18 does not interfere with the control unit 40.

[Configuration . . . Control Unit 40]

As described above, the control unit 40 is accommodated and held in the fixing frame 13. In the present embodiment, a PWM unit is used as the control unit 40. The PWM unit is an electronic part that controls a rotational speed of the electric motor 6 of the fan 5, and is electrically/mechanically connected to the electric motor 6 via an unillustrated wire.

In the control unit 40, as shown in FIG. 4, a power board 41 and a CPU board 45 are arranged facing each other.

A high-voltage current is supplied to the power board 41 from an external high-voltage power source (not shown). A switching device 42 composed of a transistor is attached to a surface of the power board 41 on a side facing the CPU board 45 (a front side). A heat transfer plate 44 that performs thermal conduction between the switching device 42 and a heat sink 50 described later is embedded in the power board 41, and the heat transfer plate 44 penetrates from a front to a back of the power board 41. When the power board 41 and the CPU board 45 are attached, one of surfaces of the heat transfer plate 44 comes into close contact with the switching device 42, and the other of the surfaces comes into close contact with a heat transfer projection 53 of the heat sink 50 described later.

A CPU 37 that controls an operation of the switching device 42 is provided on the CPU board 45. When a control signal from the CPU 37 is transmitted to the power board 41 and input to the switching device 42, the switching device 42 is operated. Accordingly, a high voltage supplied from the high-voltage power source is applied to the electric motor 6 of the fan 5, and the fan body 7 is rotationally driven at a desired speed. The switching device 42 generates heat in association with the operation of the switching device 42.

The above respective elements of the control unit 40 are covered with a cover 49.

The control unit 40 includes the heat sink 50 that functions as the heat dissipater. The heat sink 50 is arranged facing the power board 41, and when the switching device 42 of the power board 41 generates heat, the heat sink 50 dissipates the heat to prevent a temperature of the switching device 42 from exceeding a permissible range.

The heat sink 50 includes a flat plate-like sink body 51, the plurality of heat dissipation pins 52 that are provided on one surface side of the sink body 51, and the heat transfer projection 53 that is provided on the other surface side of the sink body 51. In the heat sink 50, the sink body 51, the heat dissipation pins 52, and the heat transfer projection 53 are integrally formed by casting aluminum alloy.

In the heat sink 50, the heat transfer projection 53 is arranged facing the power board 41, and the power board 41 and the CPU board 45, and the sink body 51 are fastened together with bolts. When the sink body 51 is fixed to the fixing frame 13 of the shroud 10, the control unit 40 is held by the shroud 10. In this state, a distal end of the heat transfer projection 53 of the heat sink 50 is in close contact with the heat transfer plate 44, and the switching device 42 of the power board 41 and the heat sink 50 are thermally coupled together.

In a state in which the heat sink 50 is fixed to the shroud 10, the heat dissipation pins 52 penetrate the through window 14 formed inside the fixing frame 13, to be accommodated in the pin accommodation chamber 15 as shown in FIG. 3. Therefore, the heat dissipation pins 52, which are a part of the heat sink 50, are exposed on the suction side of the shroud 10.

When the fan 5 rotates, air on the suction side is sucked in, passes through a gap of the impeller 7 b of the fan body 7, and is discharged to the discharge side as the air flow. At this time, as shown in FIG. 3, a part of the generated air flow flows from an outer peripheral side toward an inner peripheral side along the base 11 of the shroud 10 (reference character A in FIG. 3), and it is understood that the pin accommodation chamber 15 is on a way of the air flow A. The air flow A has a lower flow velocity than, for example, the air flow passing through an inner side of the outer ring 17 of the casing 16. The plurality of heat dissipation pins 52 are arranged in a zigzag grid shape with respect to the air flow A, and the air flow A passing through the pin accommodation chamber 15 is highly likely to come into touch with any of the heat dissipation pins 52. However, the arrangement of the heat dissipation pins 52 is a preferable form, and is not an element that limits the present invention.

[Operation/Effect]

The motor fan 1 having the above configuration provides the following operations and effects.

In the motor fan 1, since the control unit 40 including the heat sink 50 is provided at the corner 12 of the shroud 10 (the base 11), the control unit 40 does not interfere with the air flow passing through the discharge grill 18. Therefore, performance of the motor fan 1 is not deteriorated, and the control unit 40 also does not become a cause of noise generation. Also, since the control unit 40 is arranged at the corner 12 that is easily accessed, it is easy to perform maintenance and inspection works of the motor fan 1.

Moreover, in the motor fan 1, the heat dissipation pins 52 of the heat sink 50 are exposed in the pin accommodation chamber 15 that is on the way of the air flow A generated when the motor fan 1 is driven. Therefore, since the heat generated in the switching device 42 while the motor fan 1 is being driven reaches the heat dissipation pins 52 through the heat transfer plate 44 of the power board 41, the heat transfer projection 53 and the sink body 51 of the heat sink 50, the heat is also cooled by heat exchange with the air flow A, and is thereby dissipated with high efficiency. While the air flow A passes through the heat dissipation pins 52 (the heat sink 50), its flow velocity is low, so that noise generation can be minimized. This means that an effect of suppressing a pressure loss of the air flow by providing the heat sink 50 can be also expected.

In the motor fan 1, since the pin accommodation chamber 15 that is depressed from the base 11 is provided, and the heat dissipation pins 52 are accommodated therein, a length of the heat dissipation pins 52 can be extended by a length of the pin accommodation chamber 15 as compared to a configuration in which the heat dissipation pins 52 are caused to project from the surface on the discharge side of the base 11. Therefore, heat dissipation efficiency by the heat dissipation pins 52 can be increased. If the heat dissipation pins 52 are caused to project from the surface on the discharge side of the base 11, and the length is set to about the same length as that in the present embodiment, distal ends of the heat dissipation pins 52 project from the base 11, and possibly interfere with a member that fixes the motor fan 1.

Second Embodiment

Next, a second embodiment according to the present invention will be described. Since a basic configuration of the second embodiment is the same as that of the first embodiment, the second embodiment will be described below by focusing on a difference from the first embodiment.

As shown in FIG. 5, a motor fan 2 of the second embodiment includes a fixing stand 113 corresponding to the fixing frame 13. Unlike the fixing frame 13, the fixing stand 113 includes a stand board 115 that is solid except an inlay insertion path 114 at a distal end.

Subsequently, in the motor fan 2, the power board 41 includes an inlay 48 that is thermally connected to the switching device 42 in the control unit 40. The inlay 48 is formed of copper or copper alloy having a high thermal conductivity, with one end penetrating the power board 41 to come into close contact with the switching device 42, and the other end penetrating the inlay insertion path 114 of the stand board 115 of the fixing stand 113 to come into close contact with the sink body 51 of a heat sink 60. The heat sink 60 can be considered to be provided with the inlay 48 instead of the heat transfer projection 53 of the first embodiment. Also, the heat sink 60 is arranged only on the suction side with respect to the stand board 115, and is entirely exposed on the suction side.

The motor fan 2 provides the following effect in addition to the same effects as those of the motor fan 1 of the first embodiment.

While the through window 14 is formed at the distal end of the fixing frame 13 of the first embodiment, the motor fan 2 employs the stand board 115 that is solid except the inlay insertion path 114. Therefore, a shroud 20 of the second embodiment has higher rigidity than the shroud 10 of the first embodiment.

Note that the heat generated in the switching device 42 during driving reaches the heat dissipation pins 52 through the inlay 48 of the power board 41 and the sink body 51 of the heat sink 60 in the motor fan 2.

Third Embodiment

Next, a third embodiment according to the present invention will be described. Since a basic configuration of the third embodiment is the same as that of the first embodiment, the third embodiment will be described below by focusing on a difference from the first embodiment.

In a motor fan 3 of the third embodiment, as shown in FIG. 6, a shroud 30 is integrally formed including a heat sink 70 by casing aluminum alloy.

While the heat sink 70 includes the sink body 51, the heat dissipation pins 52, and the heat transfer projection 53 similarly to the heat sink 50, the sink body 51 is provided so as to close the through window 14 of the fixing frame 13 (the first embodiment).

Since the heat sink 70 is formed integrally with the shroud 30, the motor fan 3 provides the following effects in addition to the same effects as those of the motor fan 1 of the first embodiment.

As a path through which the heat generated in the switching device 42 is dissipated, a path from the sink body 51 to the shroud 30 is provided in addition to a path through the heat transfer plate 44 of the power board 41, the heat transfer projection 53, the sink body 51, and the heat dissipation pins 52 of the heat sink 70, so that a high heat dissipation effect can be expected in the motor fan 3.

Furthermore, since the solid sink body 51 forms a portion of the shroud 30, and the shroud 30 does not have a through hole like the inlay insertion path 114 of the second embodiment, rigidity of the shroud 30 can be increased as compared to the second embodiment.

Also, in the motor fan 3, it becomes unnecessary to attach the heat sink 70 to the shroud 30.

Although the embodiments of the present invention have been described above, the constitutions described in the aforementioned embodiments may be freely selected or appropriately changed into other constitutions without departing from the scope of the present invention.

Although the heat dissipation pins 52 of the same height are formed in the present embodiment, heat dissipation pins of different heights can be formed in the present invention. In this case, as shown in FIG. 7, it is preferable that the heat dissipation pins 52 close to an outer periphery of the shroud 10 (an upper side in the drawing) have a large height, and on the contrary, the heat dissipation pins 52 close to an inner side of the shroud 10 (a lower side in the drawing) have a small height. Since the fan 5 is arranged inside the shroud 10, the height is decreased in order to reduce noise by the heat dissipation pins 52, while the height of the heat dissipation pins 52 provided at a position far from the fan 5 is increased in view of the heat dissipation effect.

Although the heat dissipation pins 52 are used as a member for heat dissipation in the present embodiment, the present invention is not limited thereto, and for example, a form in which thin plate-like fins are provided at intervals, or a dimple-shaped form in which concavities and convexities are provided on the surface on the suction side of the sink body 51, or the like can be employed. Also, although the heat dissipation pins 52 as a part of the heat sink 50 and the surface of the sink body 51 where the heat dissipation pins 52 are formed are exposed on the suction side in the present embodiment, an entire region of the sink body 51, or further up to the heat transfer projection 53 can be also exposed on the suction side.

Also, although the pin accommodation chamber 15 has a rectangular shape in plan view, the present invention is not limited thereto, and for example, a width of a portion corresponding to a downstream side of the air flow A can be enlarged in order to cause the air flow A to smoothly flow.

Also, the materials forming the members of the present embodiment are merely illustrative, and for example, although the heat sink 50 is formed of aluminum alloy, the heat sink 50 can be also formed of other metal materials, particularly, copper or copper alloy having a high thermal conductivity. Also, although the example in which the heat sink 50 is integrally formed is described, the heat sink may be configured by combining a plurality of members.

Although the switching device 42 is exemplified as a heat generating element in the present embodiment, a resistor is cited as another heat generating element.

REFERENCE SIGNS LIST

-   1, 2, 3 Motor fan -   5 Fan -   6 Electric motor -   6 a Rotating shaft -   7 Fan body -   7 a Boss -   7 b Impeller -   10, 20, 30 Shroud -   11 Base -   12 Corner -   13 Fixing frame -   14 Through window -   15 Pin accommodation chamber -   16 Casing -   17 Outer ring -   18 Discharge grill -   18 a Fin -   19 Rib -   40 Control unit -   41 Power board -   42 Switching device (heat generating element) -   44 Heat transfer plate -   45 CPU board -   48 Inlay -   49 Cover -   50, 60, 70 Heat sink (heat dissipater) -   51 Sink body -   52 Heat dissipation pin -   53 Heat transfer projection -   113 Fixing stand -   114 Inlay insertion path -   115 Stand board -   A Air flow 

1. A motor fan comprising: an impeller that forms a first air flow from a suction side toward a discharge side that is a back side of the suction side; an electric motor that rotationally drives the impeller; a shroud including a cylindrical casing that covers an outer periphery of the impeller, and through which the air flow passes, and a base that projects from a periphery of the casing; and a controller that is arranged on the discharge side of the base, controls rotation of the electric motor, and includes a heat generating element; a heat dissipater that includes: a flat plate-like sink body; a plurality of heat dissipation pins provided on a first surface side of the sink body; and a heat transfer projection provided on a second surface side of the sink body; wherein a heat dissipater that is at least partially exposed on the suction side, and is thermally coupled to the heat generating element suppresses a temperature rise of the heat generating element.
 2. The motor fan according to claim 1, wherein the heat dissipater is exposed on the suction side via a through window that is formed in the base corresponding to the controller.
 3. The motor fan according to claim 1, wherein the heat dissipater is arranged only on the suction side of the base, and is thermally connected to the heat generating element of the controller via a heat transfer body that penetrates the base.
 4. The motor fan according to claim 1, wherein the heat dissipater is formed integrally with the shroud.
 5. The motor fan according to claim 1, wherein the shroud includes a heat dissipater accommodation chamber that is retracted toward the discharge side with respect to the base, and the heat dissipater is accommodated within the heat dissipater accommodation chamber.
 6. The motor fan according to claim 1, wherein the heat generating element is a switching device.
 7. The motor fan according to claim 1, wherein the heat dissipater includes a plurality of heat dissipation pins.
 8. (canceled)
 9. The motor fan according to claim 1, wherein the heat dissipater is integrally formed by casting aluminum alloy. 